Means for decelerating aeroplanes



F b 22, 1966 F. K. G. NORDTORP EI'AL 3,236,479

MEANS FOR DECELERATING AEROPLANES 2 Sheets-Sheet 1 Filed Feb. 26, 1965 mvsmoly United States Patent C) 3,236,479 MEANS FOR DECELERATING AEROPLANES F Olke Karl Gustaf Nordtorp, Norrkoping, and Per Borje Fonden and Karl Ove Torgny Walander, Linkoping, Sweden Filed Feb. 26, 1965, Ser. No. 435,667 8 Claims. (Cl. 244-110) The present invention relates to means for decelerating aeroplanes on the ground or on board a ship by an arresting device, such as a net, wire or the like arranged between brakes.

This application is a continuation-in-part of our copending application Serial No. 250,349, now abandoned, filed January 9, 1963.

The problem encountered is to intercept aeroplanes, which for one reason or another are unable to stop within the available area, due for example of their speed being too great, or to the necessity for interrupting their takeoff in a late phase, or to the unsatisfactory functioning of their own braking systems. It may also be a matter of employing fixedly ground or deck-based equipment for normally bringing the aeroplane to a standstill. This, as is well known, has long been the case on board aeroplane carriers due to their limited runway areas, but similar arrangements are presently gaining a substantial use at ground airports.

Aeroplane speeds have increased immeasurably during recent years and this has resulted in increased landing speeds. Therefore, the reliability of functioning of the ground or deck-based arresting devices at ever-increasing speeds has been the optimum sought by mos-t of these devices. In recent times, this has led to aggravated dynamic problems as to the capability of these devices for withstanding the substantial acceleration forces created at such high speeds.

Arresting devices as presently known, usually consist of an element which is caused to engage the aeroplane, for example a wire intended to engage a hook depending from the aeroplane, a wire intended to ensnare the undercarriage of the aeroplane, or a net intended to catch the aeroplane by its wings. These arresting devices are anchored at both ends to braking devices which, while exerting braking forces, nevertheless let out the wires or bands contacted by the aeroplane and resistingly oppose the forward pull of the same, until the aeroplane is brought to a standstill.

T'he arresting devices, and primarily their brakes, for structural reasons, must be given a mass which is substantial in relation to the landing speeds usual at present. It is true that several attempts have been made to reduce the moving masses forming part of the system, but nevertheless it is these masses which ultimately put a limitation on the maximum speed.

In the course of the arresting operation, certain acceleration forces are created due to the masses to be set in motion. In this respect, it is possible to distinguish between different so-called jerks or load peaks caused by the forces of inertia. These are dissimilar in character or origin, and in this respect, it is possible to distinguish between the first load peak and the subsequent ones among which the second one is most frequently the most diflicult to handle.

Patented Feb. 22, 1966 The present invention relates to a means and method for reducing the magnitude of the second and subsequent load peaks and is mainly characterized in that at least one point of the arresting device, disposed between the substantially central point of the arresting device and the respective one of its brakes, is connected to at least one auxiliary brake disposed beyond the main brakes as seen from the middle of the arresting device. The auxiliary brake or brakes are also disposed beyond the main brakes as seen in the direction of movement of the aeroplane, or at least not before the main brake, in order that this shall not constitute an obstacle for the cable from the main brake. This latter might be overcome by recessing the main brakes.

To fulfill its task it is not necessary that the auxiliary brake or brakes retain their braking action during the entire runont. It is however, necessary that their braking action be long enough to be retained when the lateral movements of the cable have spread out to the brakes from the impact point. This means that the braking action must allow for a cable pull-out from the auxiliary brake for at least approximately a couple of meters.

Due to the geometry of the arrangement, the point where the cables to the main and auxiliary brake join, will be accelerated forward earlier than would be the case with a simple one-brake arrangement of the same span. Also the oscillating movements will be reduced compared to a single brake arrangement.

The properties of this system will in principle not be changed if the auxiliary brtlke is of the same size as the main brake and is performing its braking action over the entire runont of the aeroplane. Also an arrangement with three or more brakes of equal or similar size may be used, each one being further out from the center of the arrester than the previous one.

With these and other objects to be hereinafter set forth in view, we have devised the arrangement of parts and steps to be described and more particularly pointed out in the claims appended hereto.

In the accompanying drawings, wherein illustrative embodiments of the invention are disclosed,

FIG. 1 is a diagrammatic top plan view of an arresting device made in accordance with the invention and shown in different positions in the course of an arresting operation;

FIG. 2 shows an arrangement similar to FIG. 1;

FIG. 3 shows how the auxiliary brakes are connected to the main cable by means of two cables attached at different points to the main cable.

FIG. 4 shows more than one cable extending from the main cable to separate auxiliary brakes for each of the connection cables; and

FIG. 5 shows how the connection cables may ride over tension rollers.

Referring to FIGS. 1 and 2, the arresting wire is therein shown at 3, and a point thereon, located substantially intermediate of the center of the arresting wire or net 3 and one of the main brakes shown at 1, is connected an auxiliary brake shown at 2. The auxiliary brake 2 can be of equal size to the brakes shown at 1 or possess equal braking power. The brake construction can be, for example, similar to that shown and described in Patent No. 3,032,293.

The arresting wire or net 3 is shown in its inactive position at the bottom of FIG. 1 with its substantially central point indicated at 10. FIG. 1 additionally plots the positions of the arresting wire or net at different subsequent times during the arresting procedure, these different wire or net positions being respectively designated at 6, 7, 8 and 9. A wire shown at 11 connects the auxiliary brake 2 with a point on the arresting wire or net 3, and which point is, as previously stated, located between the point centrally of the wire or net 3, and the main brake 1. The fastening 20 which attaches the wires 11 to the arresting cable or net can be a quick, self-releasable coupling such as shown in Patent 602,569, although this is not altogether necessary if the auxiliary brake shall have its cable 11 long enough to provide for the required extension. In FIG. 1 the invention is illustrated in the right-hand end portion, but is shown at both sides of the cable 3 in FIG. 2. The left-hand part of the invention has been omitted from FIG. 1 to illustrate the difference in function. The counter-part of the point 5 on the left-hand side of the figure is designated by the numeral 4.

The cables 11 may be connected to elastic or flexible plastic cables 8 and 21. That is to say, each of the cables 11 may be made up of a steel wire and a rope of nylon or other comparable material as at 8 and 21.

Upon an aeroplane landing at high speed and hooking the arresting wire or net 3 at approximately the center point 10, the arresting wire or net will first become extended into an apex as shown at 6. The braking wire 11 will thereby be accelerated substantially directly toward the original point of engagement between the aeroplane and the wire 3, resulting in the first jerk of inertia force. Noting the right-hand side in FIG. 1, the auxiliary brake 2 now begins to function, in that its forces will tend to accelerate the point 5 forwardly. No corresponding action will take place as yet on the lefthand side, where in FIG. 1 the braking wire has been omitted for comparison.

Shortly later, as the arresting wire is in the position shown at 7, the point 5 will be accelerated forwards forcefully due to the action of the wire 11 connected to the auxiliary brake 2. In a structure as shown on the left-hand side there will be no such contribution to the acceleration and the wire 7 will tend to straighten out because the wire 11 to the auxiliary brake 2 forms a greater angle to the wire 7 than the angle in the curvature which will otherwise tend to accelerate point 5 forwardly. In the structure shown on the left-hand side this extra contribution to the forward acceleration is absent, and the wire 7 will only tend to be straightened out by the pull at its two opposite ends by the brakes 1.

In the position shown at 8, the wire 3, as shown on the right-hand side, owing to the auxiliary brake 2, has been accelerated to form an approximately straight line. In this instant, or slightly before, the second jerk of inertia force is produced because of the stretching of the wire now taking place.

In the structure of the left-hand side the same phenomenon will occur later, and the favorable effect is attained because of the possibility of thus advancing the time at which the wire 3 will first get stretched. As a matter of fact, for geometric reasons, the acceleration will increase even higher the longer its occurrence is postponed.

A further advantage in suppressing the second jerk of inertia force resides in the fact that this jerk tends to start a series of oscillations which give rise to a third, a fourth jerk and so on, of magnitudes more or less comparable to that of the second jerk of inertia force.

The auxiliary braking device 2, may be of suitable design and be constructed in a number of possible ways. In one embodiment, a small brake of conventional design per se may be installed. Since the range of action of the latter need not exceed a few meters, the quick self-releasing couplings 20 may be suitably arranged at the points 5, whereby the auxiliary braking action will be interrupted as soon as the second jerk occurs.

As heretofore stated, for comparison purposes, FIG. 1 shows the cable 11 at one side only of the braking wire or net 3, but FIG. 2 shows the arrangement with the two wires 11 in position.

The modification of FIG. 3 shows how each of the auxiliary brakes 2 may be connected to the cable or net 3 by means of two cables 22, 23 connected at different spaced points on said cable 3.

The modification of FIG. 4 shows two cables extending from the cable or net 3 to separate auxiliary brakes 24!, 25, the cables extending thereto being indicated at 26, 27.

FIG. 5 shows how the cables 28 and 29 may extend around tension rollers 30, 31. These rollers may be located in such positions that greater leeway will be had in positioning the brakes in the most suitable positions.

As will appear from the foregoing, the auxiliary brakes are located. a further distance awayfrom the central point of the braking cable 3 than the main brakes. The auxiliarybrakes are also located behind the main brakes with respect to the movement of the aeroplane to be halted.

Having thus described an embodiment of the invention in a number of forms, it is obvious that the same is not to be restricted thereto, but is broad enough to cover all structures coming within the scope of the annexed claims.

What we claim is:

1. A means for decelerating aeroplanes on a landing area comprising, an arrester extending between main brakes which resist the pull imposed on said arrester upon contact by an aeroplane in landing, one or more auxiliary brakes at each side disposed beyond the main brakes as taken from the middle point of the arrester and. beyond the main brakes as. taken in the direction of the movement of the aeroplane, and connection cables extending between said auxiliary brakes and points on the arrester located between one of the main brakes and the central point of thearrester, said auxiliary brakes serving to reduce the magnitude of the second and subsequent load peaks placed on the arrester by said decelerating aeroplane.

2. A means for decelerating aeroplanes as provided for in claim 1, wherein the cables to the auxiliary brakes are separated from the arrester by quick-release couplings after a braking action from the auxiliary brake after a minimum order of magnitude of a few meters.

3. A means for decelerating aeroplanes as provided for in claim 1, wherein a part of the cable connecting the arrester with the auxiliary brakes consists of a flexible member.

4. A means for decelerating aeroplanes as provided for in claim 1, wherein the main brakes and the auxiliary brakes are of substantially the same size and provide their braking over substantially the same aeroplane runout.

5. A means for decelerating aeroplanes as provided for in claim 1, wherein pulleys constitute points from which the cables extending to the arrester are free to move, the brakes being conveniently placed anywhere in the vicinity of said pulleys.

6. A means for decelerating aeroplanes as provided for in claim 1, characterized in that the connection cables are connected to the auxiliary brakes at one end and are each connected to the arrester by a self-releasing joint adapted to disconnect the cables of the auxiliary brakes from the arrester as soon as the maximum braking distance of the auxiliary brakes hasbeen utilized.

7. A. means for decelerating aeroplanes upon landing comprising, a pair of spaced main brakes, an arrester stretched between the same for contact with the landing aeroplane, a pair of auxiliary brakes located beyond the main brakes in the direction of travel of the aeroplane, a pair of cables connected to each of the auxiliary brakes at one end, each pair of said cables being attached at spaced points to the arrester, which points of connection of said cables to the arrester are located between the center point of the arrester and the main brakes, said auxiliary brakes serving to reduce the magnitude of the second and subsequent load peaks placed on the arrester by said decelerating aeroplane.

8. A means for decelerating aeroplanes as provided 5 References (Iited by the Examiner FOREIGN PATENTS 10/1959 France. 1/1960 France.

10 MILTON BUCHLER, Primary Examiner.

L. C. HALL, Assistant Examiner. 

1. A MEANS FOR DECELERATING AEROPLANES ON A LANDING AREA COMPRISING, AN ARRESTER EXTENDING BETWEEN MAIN BRAKES WHICH RESIST THE PULL IMPOSED ON SAID ARRESTER UPON CONTACT BY AN AEROPLANE IN LANDING, ONE OR MORE AUXILIARY BRAKES AT EACH SIDE DISPOSED BEYOND THE MAIN BRAKES AS TAKEN FROM THE MIDDLE POINT OF THE ARRESTER AND BEYOND THE MAIN BRAKES AS TAKEN IN THE DIRECTION OF THE MOVEMENT OF THE AEROPLANE, AND CONNECTION CABLES EXTENDING BETWEEN SAID AUXILIARY BRAKES AND POINTS ON THE ARRESTER LOCATED BETWEEN ONE OF THE MAIN BRAKES AND THE CENTRAL POINT OF THE ARRESTER, SAID AUXILIARY BRAKES SERVING TO REDUCE THE MAGNITUDE OF THE SECOND AND SUBSEQUENT LOAD PEAKS PLACED ON THE ARRESTED BY SAID DECELERATING AEROPLANE. 